Process for preparing non-woven fabrics



Sept. 15, 1970 I I 0 ETAL 3,528,147

PROCESS FOR PREPARING NON-WOVEN FABRICS Filed April 8. 1968 70 60 9b 10o 1io 1E0 130 Temperature i United States Patent O PROCESS FOR PREPARING NON-WOVEN FABRICS Aldo Fior, Goteborg, Sweden, and Mauro Navone, Milan,

Italy, assignors to Montecatini Edison S.p.A., Milan,

Italy, a corporation of Italy Filed Apr. 8, 1968, Ser. No. 719,310 Claims priority, application Italy, July 25, 1967, 18,760A/ 67 Int. Cl. D04h 18/00 US. Cl. 28-722 6 Claims ABSTRACT OF THE DISCLOSURE Non-woven fabrics made up of non-woven lap and backing prepared by making up a non-woven lap comprising a blend of fibers containing from to 50% of heat-shrinkable fibrous component, laying such lap upon a backing, mechanically interlocking portions of the lap with the backing, as by passage of the lap-backing through a needle-punching machine, and heating so as to shrink the fibrous component.

BACKGROUND OF THE INVENTION Field of the invention The present invention concerns fabrics of the nonwoven type made of synthetic fibers, and further relates to a process for preparing such fabrics.

Description of the prior art It is known that the preparation of non-woven fabrics, particularly of carpets, is carried out according to a process that comprises the following general steps:

carding the fibers so as to form a lap or batt;

laying the lap over a support, or alternatively, laying two laps over and under a support to form a sandwich with the support between the two laps;

securing the lap to the support, as by passing the lap/ support through a needle-punching machine;

coating or spraying or dipping of the lap/ support assembly with binders, in particular, elastomers, acrylic resins, rubber or the like, which serve to bind the lap to the support; and

passing the thus coated assembly through an oven such that the binders are dried and/ or polymerized to thus firmly bind the lap to the support.

The use of binders, e.g., acrylic resins and/ or other glue materials frequently results in a number of disadvantages. Thus, often merely a slight rubbing on the fabric surface will result in streakings thereon, by virtue of the resin being exuded from the bottom of the fabric.

Often the fabric exuding the binders will become gummy, tacky or sticky so that it soils easily. Finally, the binders, in particular on fabrics made up of polyamide and/ or polypropylene fibers, often reduce the light fastness of dyes.

The present invention provides a process whereby the above mentioned drawbacks are virtually eliminated.

This invention provides fabrics wherein at least one lap comprises a fiber blend containing from 5% to 50% by Weight of a thermo-shrinkable fibrous component, desirably of chlorovinyl material.

SUMMARY OF THE INVENTION We have surprisingly found that non-streaking fabrics that are neither gummy nor tacky, and which have a good light fastness for dyes, and show, above all, better wear characteristics such as a minor dirt receptivity and a good abrasion resistance, may be obtained by preparing a fiber blend containing from 5 to 50% of thermo-shrinkable fibrous component, forming a lap from such blend, laying such lap over a support (or forming a sandwich with such support disposed between two such laps), mechanically interlocking the lap with the support, e.g., in conventional manner, as by passing the lap/support through a pinning (needle-punching) machine, optionally applying to the support, as by coating, spraying or dipping, a conventional binder such as a polyvinyl chloride plastisol, and heating the lap/support composite, as by passage through an oven chamber. When the non-woven fabrics are used to produce paving tiles for floors the fabric support can be eliminated.

By operating in this Way, the drawbacks known to the prior art are markedly reduced or overcome altogether. The use of a lap containing thermo-shrinkable chlorovinyl fiber permits one to avoid altogether the use of binders, or alternatively to reduce the amount of binder employed as compared to that amount required by the prior art. In particular, the use of acrylic resins or other binders that tend to promote soilability, reduction of light fastness, or the like may be avoided altogether.

The use of a lap containing thermo-shrinkable chlorovinyl fibers reduces or altogether avoids the need of binders inasmuch as during heat treatment, as by passage through an oven or drying chamber, the thermo-shrinkable chlorovinyl fibers shrink, thereby pulling with them the other fibrous component of the blend and hence fixing the lap to the support.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The laps to be used in accordance with this invention comprise fiber blends containing from 5 to 50% of thermo-shrinkable fibers, desirably polychlorovinyl fibers, together with one or more other fibrous materials that either are not heat shrinkable or are not so heat shrinkable as the foregoing thermo-shrinkable fibrous material. Particularly suitable for use as such other fibrous material are polyamide, polyester, polypropylene or acrylic fibers, optionally modified by the addition of modifying agents so as to increase the dyability.-

The thermo-shrinkable polychlorovinyl fibers are commonly known fibers consisting substantially of polymers of vinylchloride, i.e., polyvinyl chloride or copolymers of vinyl chloride with another ethylenically unsaturated monomer copolymerizable therewith, such polymers or copolymers being used either alone or in admixture with another polymeric material such as highly chlorinated polyvinyl chloride, nitrocellulose, or the like. Such chlorovinyl fibers are prepared by conventional wet or dry spining of, e.g., polymers or copolymers of vinyl chloride, such polymeric materials being obtained by known emulsion, suspension or bulk polymerization processes.

The support is generally in the form of a fabric backing made up of jute, cotton, hemp, polypropylene ratfia, continuous polypropylene filament fabrics, or of other conventional backing material.

If the backing is to be coated, it is advantageous to use as the coating material a polyolefin film of polyethylene, polypropylene, or the like. Such a film may be coupled to, e.g., laid upon, the backing before passing the whole through the oven. During passage through the oven the film is firmly anchored to the backing. Alternatively the coating substance (acrylic or polyvinyl resins, latex of natural or synthetic rubber, P.V.C. plastisol) may be applied to the manufactured article by total (dipping) or partial (coating of the back side) impregnation.

The fabric is then best heat treated, desirably in an oven preferably at from about to C. for a time period of from 5 to 20 min.

Dying of the fabrics may be carried out according to conventional techniques.

The chlorovinyl fibers used in the present invention show a variable heat shrinkage, depending upon the method used in their preparation and upon the possible materials admixed with the polymers.

The figure illustrates the shrinkage of chlorovinyl fibers suitable for the present invention. The area within the hatched zone, shown by way of illustration, indicates preferred shrinking ranges for the chlorovinyl fibers. Line 1 illustrates very highly shrinkable fibers (for instance, those sold under the trademark Movil N of the Italian Company Polymer S.p.A.); line 2 illustrates much less shrinkable fibers (for instance, those sold under the trademark Movil T of Polymer S.p.A.).

The amount of thermo-shrinkable chlorovinyl fibers to be employed in the blend will depend upon the degree of shrinkage, in the sense that smaller quantities would be used in the blend when highly shrinkable fibers were employed, and higher amounts thereof would be used when low shrinkage fibers were employed.

The shrinkage of the non-woven fabric layer is also influenced by (1) the structure of the fabric particularly its thickness, (2) the characteristics of the backing, (4) the nature of the thermal treament (temperature and time) (3) the pinning treatment index (number of penetrations per surface unit 100-200 penetrations/cm. As regards pinning treatment index, generally a smaller freedom of the chlorovinyl fibers and hence a smaller dimensional variability correspond to a more compact fabric.

The amount of shrinkage attained in accordance with the present invention is not necessarily as great as that illustrated in the figure. That is, inasmuch as there are constraints exerted upon the chlorovinyl fibers by virtue of their having been mechanically interlocked within the support, upon heating they are not free to shrink as much as they would want to in the absence of such constraints. The amount of shrinkage is nevertheless sufiicient to achieve a firm effective fastening of the lap to the support.

The fibers suitable for use in this invention and referred to herein are well known. See, e.g., text by M. Sittig entitled Synthetic Fibers From Petroleum (1967) at pages 100-106 which describe polyamides, page 205 which describes polyester, pages 228-248 which describe acrylics, and pages 259-271 which describe polyolefins; the text by R. Hill entitled Fibers From Synthetic Polymers (1953); the text by F. Fourne entitled Synthetische Fasern (1964); the articles by E. Fricser, Textil-Rundschau 14, 1-6 (1959); and the article by R. W. Henerieff in Fibers, p. 113 (April 1957).

The following examples will further illustrate this invention.

Example 1.A blend was prepared consisting of:

85 parts (by weight) of polypropylene fibers modified by the addition of basic polycondensates of epichlorohydrin with at least one amine preferably with dicyclohexylesamethylenediamine and with piperazine (as described in the Belgian Pats. No. 591,201, No. 606,306 and No. 620,706) having a count of 17 d./tex (15 den.), and a staple length of 60 mm.;

15 parts (by weight) of polyvinyl chloride fibers having a count of 5.6 d./tex (5 den.), a staple length of 60 mm., and shrinking characteristics corresponding to line 1 of the figure.

The blend was transformed into a lap by passing it through a carding machine of the wool type. The lap, weighing about 700 g./m. was disposed over a fabric formed of jute fabric weighing 320 g./m.

The backing/lap composite was then passed through a conventional needle-punching machine undergoing 180 penetrations/omit Thereafter a polyvinyl chloride plas- 4 tisol was spread over the backing. The fabric was then introduced into an oven at a temperature of 120 C. and kept there for about 12 minutes.

The fabric showed a very good anchorage of the lap to the backing. It was essentially non-inflammable and displayed a good abrasion resistance. In fact, the weight loss of 100 cm. of this fabric submitted to an abrader of the Cesconi type, after 3000 cycles under a 230' g./cm. load, amounted to only 1.05 g. A comparison fabric having the same characteristics of the above lap weight (700 g./cm. of the above backing weight (320 g./cm. and the same penetration numbers (180 pen/cm?) had, after pinning, undergone, a total dipping with acrylic resin in aqueous emulsion, and thereafter was dried; said comparison fabric consisting of 100% polypropylene fibers modified with said condensation products, abraded under the same conditions, showed a weight loss of 1.28 g.

(In the Cesconi abrader a fabric sample is submitted to a given number of abrasion cycles under a given load, by means of a mobile arm having a reciprocating movement and lined with glass paper of 600 grit size.)

Weight losses of the same order were obtained when the foregoing two specimens were tested according to (1) the Impeller Tumble Method reported by the Am. Assn. of Textile Chemists Tentative Method 93- 1966 and (2) according to ASTM-D-1l75.

Example 2.-A fiber blend was prepared consisting of:

90 parts of nylon polyamide fibers (polyhexamethylenadipamide) with a count of 17 d./tex (15 den.), staple size 60 mm.;

10 parts of polyvinyl chloride thermo-shrinkable fibers,

5.6 d./tex (5 den.), staple length 60 mm. The shrinkage of this last fiber is the same as that of Example 1.

This fiber blend was transformed into a lap by passing it through a carding machine of the wool type. The lap was arranged over a support of polypropylene ralfia. (See BritishPlastics, January 1966, pp. 38-39.) This support was a woven backing having 6 filaments/cm., a count of 1000 d./tex in both the wrap yarn and the weft yarn.

The lap/backing composite was then passed through a needle-punching machine, undergoing 160 pen/cm. and through a total foulard impregnation in acrylic resins aqueous emulsion (the solid residue of the resin over the total weight of the article being 12% Thereafter the fabric was introduced into a heating oven at a temperature of 135 C. and kept there for about 8 minutes.

The fabric showed a good anchorage of the lap to the backing, and showed a good abrasion resistance.

Example 3.-A blend of fibers was prepared consisting of:

parts of acrylic fibers, count 17 d./tex (15 den.),

staple length 60 mm.;

20 parts of polyvinyl chloride thermo-shrinkable fibers,

5.6 d./tex (5 den.), staple length 60 mm. The shrinkage of this fiber is the same of that of Example 1.

The blend was transformed into a lap by passing it through a carding machine of the wool type. The lap was then disposed over a backing made of a fabric of continuous polypropylene filaments, having a count of 1.00 d./tex and consisting of 70 filaments. The lap/backing composite was then passed through a needle-punching machine and a polyvinyl chloride plastisol spreading as described in Example 1.

The fabric was then introduced into an oven at a term perature of 135 C. and kept there for about 10 minutes. The fabric showed a good anchorage of the lap to the backing, and showed a good abrasion resistance.

Example 4.A blend was prepared consisting of:

parts (by weight) of polypropylene fibers, having a count of 17 d./tex (15 den.) and a staple length of 60 15 parts (by weight) of polyvinyl chloride staple fibers, having a count of 5.6 d./tex den.), and a staple length of 60 mm., the shrinkage characteristics being the average of the values of line 1 and line 2 in the figure.

The blend was transformed into a lap by passing through a carding machine of the wool type. The lap was then disposed over a backing made of a fabric of continuous polypropylene filaments having a count of 1.100 d./tex and consisting of 70 filaments.

The composite was passed through a pinning machine (140 penetrations/cm?) foulard dipping with an acrylic emulsion bath in which the acrylic resin shows a solid residue of 15% over the total weight of said composite, and then introduced into an oven at a temperature of 125 C. and kept there for about 15 minutes.

The fabric showed, on testing with a Cesconi abrader under the same conditions of Example 1, a weight loss of 0.9 g. A control sample of 100% polypropylene fibers, obtained with the same fabric support, the same penetrations (140) per cm. and the same foulard dipping with an acrylic emulsion (solid residue 15 showed a weight loss of 1.15g.

Example 5.-A blend was prepared consisting of:

80 parts of polypropylene fibers, count 17 d./tex (l5 den), staple length 60 mm.;

20 parts of polyvinyl chloride staple fibers, count 5.6

-d./tex (5 den.), staple length 60 mm. (thermo-shrinkability of line 1 of the figure).

The blend was transformed into a lap by passing through a carding machine of the wool type. The lap, weighing about 500 g./rn. was then disposed over a backing consisting of a jute fabric (250 g./m.

The composite was then passed through a pinningrnachine 150 penetrations/cm?) and a dipping in foulard with an aqueous emulsion of an acrylic resin (250 g./cm.

The fabric was then introduced into an oven at 120 C. and kept there for minutes. The weight loss of a 100 cm. sample using the Cesconi abrader, after 3,000 cycles with a 230 g./cm. load, was 0.4 g. A control sample consisting of 100% polypropylene fibers on the same support, and obtained under the same conditions i.e. with the same penetrations and the same dipping, showed a weight/loss of 0.9 g.

The sample according to the invention shows thus an abrasion resistance double than that of the comparison sample.

Example 6.A blend was prepared consisting of:

78 parts of polypropylene staple yarn, count 17 d./tex

( den.), staple length 60 mm.;

22 parts of polyvinyl chloride staple fibers, count 5.6

d./tex (5 den.) staple length 60 mm. (thermoshrinkability of 'line 1 of the figure).

The blend was transformed into a lap by passing through a carding machine of the wool type. The lap weighing about 650 g./m. was then disposed over a backing made of continuous polypropylene yarns with a count of 1100 d./tex and 70 filaments; the weight of the backing was about 150 g./m.

The composite was passed through a needle punching machine (200 penetrations/cm. and spread on the back side with a butadiene-acrylonitrile latice containing thickeners, vulcanizing agents and mineral fillers in an amount suitable to give a solid residue of 1100 g./m. the article is then introduced in an oven at 135 C. during 15 minutes. Due to the good anchoring realized through the binding action of the shrinkable fibres, the upper part which is not impregnated with the latice, shows an abrasion resistance higher than that of a carpet made of 100% polypropylene fibres and totally impregnated (in foulard) with 270 g./cm. of solid residue of an acrylic resin.

The weight loss of cm. using the Cesconi abrader after 3,000 cycles with a 230 g./cm. load was of 1.05 g. for the carpet according to the invention and 1.5 g. for the comparative carpet.

According to the present invention, the thermo-shrinkable chlorovinyl fibers, after the heat treatment (which follows the pinning), are anchored firmly to the backing, fixing thereto the other fibers of the lap.

in order to demonstrate the anchoring of the chlorovinyl fibers to the backing as well as their power of penetrating the inner part of the layer, making up the lap the following blend was prepared:

75 parts of polypropylene fibers, black colored, having a count 17 d./tex (15 den.)

25 parts of chlorovinyl fibers, White colored, having a count 5.6 d./tex (5 den), and a shrinkage as indicated by line 1 of the figure.

Pinning was effected, characterized by 150 penetrations/ cm. this pinning being carried out in the absence of any backing. The resulting sample appeared to the naked eye as having a grey color, because of the simultaneous presence on the surface of white chlorovinyl fibers dispersed in the black polypropylene fibers. A color photo of the product during this step clearly showed the grey coloring of the surface layer.

The non-woven fabric, when heated at C. for 8 minutes (in a tunnel dryer), was transformed into an article that showed a substantially black surface. In fact, the white chlorovinyl fibers, originally present in the surface layer, had shrunk because of the heat treatment and penetrated deeply the inner part of the non-woven fabric.

According to the invention it is thus now possible to obtain non-woven fabrics suitable for use as carpets, linings for walls, floors, seats, furniture, etc., which fabrics exhibit not only particularly advantageous mechanical characteristics, but which also exhibit remarkable esthetic features and hence which are economically desirable in the furnishings field. Thus, appropriate selection of the proper amount of thermo-shrinkable chlorovinyl fibers in the blend (for the lap), which amount is dependent upon such factors as shrinking characteristics, quantity and color of the non-woven fabric forming fibers, etc., enable one to obtain a wide range of well proportioned colors having great esthetic appeal.

It is to be understood that the presence of the backing is not critical.

The said pinning-machine (or needle punching-machine or needle-loom) are well known in the art (see G. Robinson, Carpets, Pitman 1966; and also Technical Bulletin M6 of Monsanto, May 1967) and are exemplified by e.g. the Garnett Bywater, Hunter, Dilo, Fehrer needleoom.

While the foregoing description has been made with reference to the use of blends of fibers (for the lap) wherein a chlorovinyl fibrous material is employed as the more heat-shrinkable material of the blend, it is important to note that the invention is also applicable to the use of blends wherein, as the fibrous component that is the more heat-shrinkable, something other than chlorovinyl fibers is employed.

It will thus be seen that the gist of this invention is in the provision of at least two different fibrous materials as components of the blend from which the lap is made. These different fibrous materials must be so selected that, upon heat treatment, differential shrinkage occurs therebetween. Thus, upon disposing the lap made from such a blend over a fabric support, mechanically interlocking portions of such lap with said support, as bypassing the lap/ support through a needle-punching machine and an appropriate impregnation, subsequent heating results in differential shrinkage of the fibers within the lap, thereby firmly anchoring the lap'to the support.

It is preferred that the mechanical interlock between the lap and the support is such that tufts of the lap material extend all the way through the support. Thus, such a type of mechanical interlock is readily obtained by use of a needle-punching machine, whereby tufts of the lap material actually extend through the support and protrude somewhat through the opposite side. Differential shrinkage resulting from subsequent heat treatment causes the more shrinkable fibers to grab the less shrinkable fibers.

It should be noted that although it is desirable, it is not essential that the tufts of lap material extend all the way through the support. Thus, so long as these tufts penetrate the interior of the support, subsequent heating with the resultant differential shrinkage insures the formation of a mass or ball of material within the support, thereby anchoring the lap to the support.

While it is preferred to employ in the lap at least two fibrous materials having different heat shrinkage characteristics, it is to be noted that virtually equivalent results can be obtained by employing but a single fibrous material made up of at least two components having different heat shrinkage characteristics. Thus, multicomponent or conjugate fibers are well known in the art. Such a fiber is made up of two or more distinct components extending longitudinally of the fiber, e.g., in side by side relation, sheath-core relation, or the like. Accordingly, formation of a lap from such multicomponent fibers, mechanically interlocking such a lap with a fabric backing, and then heating, will result in differential shrinkage of the components with a consequent bulking or bunching of the fibers, thus resulting in a tenacious anchoring of the lap to the base.

Variations can, of course, be made without departing from the spirit of our invention.

Having thus described the invention, what we desire to secure by Letters Patent and hereby claim is:

1. A method of preparing a composite fabric comprising a non-woven lap secured to a fabric backing, this method comprising, forming a fibrous lap composed of at least two components, one of said components being more heat shrinkable than the other, disposing said lap upon a fabric backing, needling said lap with said backing so that portions of said lap penetrate the interior of said backing to anchor said lap thereto, and heating to efiect differential shrinkage of said components, whereby said lap is more firmly anchored to said backing by virtue of the differential shrinkage of said components.

2. The method of claim 1 wherein one of said components makes up a portion of the fibers in said lap and another of said components makes up the remainder of said fibers in said lap.

3. The method of claim 1 wherein said two components are present in each of the fibers making up said lap so that said lap is made up of multicomponent fibers.

4. The method of claim 1 wherein said lap contains from about 5 to by weight of thermo-shrinkable chlorovinyl fibers and correspondingly from about to 50% by weight of less thermo-shrinkable fibers.

5. The method of claim 4 wherein said needling is effected by passing the lap/backing through a pinning machine.

6. The method of claim 4 wherein the less thermoshrinkable fibers are selected from the group consisting of fibers of polyamides, acrylic fibers, polyester fibers, and polypropylene fibers.

References Cited UNITED STATES 'PATENTS 3,216,082 11/1965 Goy 2872.2 3,235,935 2/1966 Daruwalla 2872.2 3,272,898 9/ 1966 Knee.

3,407,461 10/1968 Stevenson et a1 2872.2 2,825,958 3/1958 Chandler 2872.3 X 3,317,335 5/1967 Marrinan et al. 2872.2 X 3,377,231 4/1968 Newman 2872.2 X

FOREIGN PATENTS 1,080,222 8/ 1967 Great Britain.

LOUIS K. RIMRODT, Primary Examiner 

